Aircraft wing



NOV- 2 6, 1940- i-LH. STEWART AIRCRAFT WING Fled'July 14, 1958 6Sheets-Sheet 1 lllllll IIL.

m@ .mm r l am i, u 2 m s m-zn q m mv W2 i ATTORNE Nov. 26, 1940. H. H.STEWART AIRCRAFT WING Filed July 14, 1938 6 Sheets-Sheet 2 INVENTOR. I

ATTORNEY Nov. 26, 1940. H H STEWART 2,223,335

AIRCRAFT WING Filed July 14, 1938 G Sheets-Sheet 5 H. H. STEWART'AIRCRAFT WING Nov. 26, 1940.

Filed July 14, 1958 6 Sheets-Sheet ATToRN Y Nrw.v 26, 1940. H, H STEWART2,223,335

AIRCRAFT WING -Fled July 14, 1958 6 Sheets-Sheet 5 A, if .5; 'u M mATTORNEY Nov. 26, 1940. H. H. STEWART AIRCRAFT WING l e sheets-sheet eFiled July 14, 1938 Fig. 1 isa plan Patented Nov. 26, 1940 UNITEDSTAT-Es 2a23-,sse *Amcnm wma Harry H. SteWart,FIuShing, N. Y.``pplicaton .'llly 14, 1938, Serial No. 219,\138

0 contended that there is little need of a variable l camber airfoil.However, consideration of the aerodynamics of this problem proves that asuit' able variable camber airfoil has many advan tages overv airfoilshaving aps. The main object o f this invention is to provide an improvedairfoil which is readily variable in thickness and' camber within a'wide range, so that abasic thin section wing may be changed to aselected thick section wing, and vice versa,

0 while at all tiines maintaining a smooth and proper cambercurvaturethat develops the maximuni desirable characteristics for `any selectedvariation but in no way affects the .inherent rigidity of the normalwing structure.`

Another important object of the invention is to provide a simple andlight mechanism for this purpose which may be conveniently incorporatedfin modern airplane rwing/ structures, particularly in conventional metalskin wing sections. t A further object of the invention isito provide anairplane wing which is simple and economical to construct andis sodesigned vthat parts of the skin are readily removable independently ofother parts, Vto permit access to the interior of the wing forinspection, repair or replacement of portions of theca'mber varyingmechanism. -These and other objects and the novel features ofthisinventlon will becomeapparent from the following descriptionconsidered with the accompanying drawings, in which: 'l Y w view of ametal airplane wing embodyingthis invention, showing parts of theinterior mechanism in dotted lines;

-1iig.`2V is a front or leadingedge elevation of the wing shown in Fig.1, illustrating/in solid outline the basic high speed wing thickness andin dotted outline the greater relative 4thickness obtainable for highlift characteristics;

Figs. 3 and 3d when. placed end to end, together illustrate on anenlarged scale, a transverse section of .the wing, taken on the .lines/3--3 of Figs. 1 and 2; showing the invention embodied:2 in4 a two-sparcross-rib'unstressed skin type of wing structure, the movable upper skinbeing 1 1 claims. (ci 24e-4.4)

shown in solid lines inthe basic wing position and in. dotted lines inan extended or auxiliary position, and a conventional ilapbeing shown infull and dotted lines in different positions..

Fig. 4V is a large scale sectionalview, taken on 5 l linesl-I of Figs. 1and 3, showing an assembly l comprising a portion of a cross-rib, theupper skin sections and associated parts; A Fig. 5 is a large scale'sectional view, taken on lines Figs. 6 and 6a when placed end to-endfiige'ther 4fillustrate on an enlarged scale, a transverse. secltionof a wing, taken on Ylines corresponding to l5, 6 6 oi' 1 and 2, showingthe invention embodied in a multi (extruded'section) spar and stressedskin type of wing structure;

Fig. 7 is' a large scale sectional view taken on line 'if-'i of Figs. 1and 6, and showing a part of 20 a torque tube, a coupling thereof, acrank there- A on, and a push. rod connected to `the crank, all xconstituting parts of mechanism for varying the vcamber of the upperskin of the wing; y

Fig. 8 is an enlarged sectional view taken 'on 2 lines 8-8 of Figs. 1and 6, showing the construe;

tion of overlapping portions of the upper skin sections; f

Figs; 9 and 10 are sectional views, taken reo spectively on lines 9-9and--IlI-IU of Fig. 3 showing alternative closure constructions for theends of the variable camber' wing;

Figs. 11 and 1 2 are respectively a plan view and a transversesectionalview of another Vwing 35 embodying this invention Vand providedwith1 huid-actuated mechanism for varying the cam- Abei' of an airplaneFigs. 13, 14, 15 and 16` are views illustrating iiuid supply and controlmechanisms which may be employed to actuate suitable devices for vary'-ing the camber ofia wing;

, Fig. 17 is an enlarged sectional view of a liquidV reservoir andVassociated mechanism lfor actuating devices used to vary thecamber of aWing: and 45.

Figs'.l 18 and 19' are sectional views respectively illustrating asingle-acting and a double-acting expansion cylinder and an, upper wingskin to which they are connected. l L

' Figs. 1, 2, 3,3m, 4 and 5 illustrate the inventi n 50 embodied in atwo-spar cross-rib unstressed metal skin type of wing structure. 'I'hetwo conventional metal spars 3B, 38j are nearly parallelI land arelocated respectivelynear the foreand aft portions of the wing. Eachmetal cross-rib 55 5 5, of Figs. 1 and 3, showing an assemmy Io' .spanof the wing.

comprises a movable rib .I6 slidable between a pair of fixed ribs I1.These cross-ribs are spaced apart and their; number is determined by theThe'ribs I1 of each pair of iixed ribs are slightly spaced apart toprovide slots and are formed in sections which are sel to provide acontinuous lower skin. The several panels of the lower skin may thus bemade removable and replaceable independently4 of one another so that thespace between any two crossribs willl be readily accessible by simplyremoving the panel closing such space.

'Ihe Vupper wing sheath or skin may consist of two relatively movableYmetal sections, the leading section being hinged at 34 lengthwise of theleading edge yof the wing and overlapping the trailing section which ishinged at 34' adjacent to and lengthwise of the trailing edge of thewing. The leading upper skin section may consist of a plurality of metalpanels 29, each of sufficient Width to bridge the space between twoadjoining cross-ribs and desirably to provide margins wide enough tooverlap directly above such ribs. As shown in Figs. 4 and 5, each pairof overlapping panel margins is secured by suitable means, such as a rowof screws 3i, to a metal bearing and stiiening plate 3|) which extendslengthwise of the joint atthe inside thereof. The outside of each jointis protected and reinforced by a convex metalcoverstrip 32 which extendslengthwise of the joint and is secured in place by a row of the screws3I. Spacers 33 bear against the outside of a panel margin and the insideof the strip 32,

Similarly, the trailing upper skin section consists of a pluralityv ofmetal panels 26, each of suiiicient width to bridge the space betweentwo of the upper sheath oi the wing.

adjoining cross-ribs and to provide: margins which overlap on and aresecured |by rows of countersunk screws 21 through stiffening plates 28and panels 2 6 to flanges I6' on the several movable ribs I6.A The metalbearing and stiiening plate 28 is coextensive with each flange I8' andis secured thereto and against the outside of an overlapping margin of apanel 26 by the rows of screws 21, so that each plate 30 is directlyAabove and rides upon each plate 28, and is lubricated or equipped withanti-iriction bearingsv to reduce the friction and wear of theoverlapping portions of the skin sections, when the skin sections aremoved relativelyto one another away i'rom and toward the spars 38, 38and the ribs I1 to increase or decrease the camper vIrwin be understoodthat, in order ie enema greater continuity of the upper skin surfacertheadjoining panels 29 may be arranged in abutting insteadof overlappingrelation and either screwfastened, riveted or welded in pairs to theplates 30 above the leading mbvablefribs I6; and. ady joinirigfpanels 26may be arranged in abutting relationdandsimilrly secured to flanges I6'and platesl 38. Here, the cover' strips 32' may be omitteddi desired.However. the adjoining pan- I1' on the lower ends of ,els in allinstances preferably are overlapped and screw-fastened in place asshown. In Figs 3, 3a if the movable sections of the upper wing areriveted to the movable cross-ribs, then the lower skin panels arescrew-fastened to the lower iianges of the xed ribs. In Figs. 6, 6a, thestressed skin is riveted throughout to the frame of the wing, and thepanels of the movable seotions are then screw-fastened to associatedparts.

To maintain the upper skin sections in xed relation to one another, andto guide them with .suitable clearance While they are moving relativelyto one another, each plate 30 has two or more integral threaded studs 56spaced" clear of screws 21 which extend inwardly through an equal numberof registering slots 56 in theopposed plates 28, the iianges on themovable ribs I5, and the margins of the panels 26 between s'uch ribs andflanges, as best shown in Fig. 4. These studs 56 carry nuts attheirinner ends which are safety wired to the studs at a position toprovide proper clearance. Y

As best shown in Figs. 3, 3a. and '1, the mecha' nisrn for positivelymoving the skin sections in unison outwardly from or inwardly to thebasic wing position, to vary the camber of the wing,

may comprise a main transversely extending hollow metal torquevtube I2journalled in the ribs I1 betweenthe spars 38, 38 and near the center ofthe wing, and a suitable number of short auxiliary hollow metal torquetubes I5, I5 individually journalled in the ribs I1 parallel to the maintube I2, in front of the main spar 88 and betweenthe tube I2 and therearspar 38'. 'Ihe torque tube I2 is formed in, sections approximately equalin length to the distance between two adjoining cross ribs, and thesesections are connected together by couplings 35, as shown in lFig'. '1.vA double-'arm master crank I3 is rigidly mounted on the torque tube I2adjacent each rib I1, and an auxiliary double-arm crank 43 is similarlymounted on each of the auxiliary tubes I5 and I5'. Each master crank I3and the auxiliary cranks' in une therewith adjacent each cross rib areconnected together in a group by tubular metal drag links Il, the endsof which are pivoted to appropriate arms of these cranks, so that theauxiliary tubes I5, I5' will rotate simultaneously with the main torquetube I2. The master crank and auxiliary cranks are each provided withtwo arms, one arm of.

each crank being connected by push rods I8 to parts of the movable ribsI6. As best shown in Figs 3, 3a and 4, the push rods I8 are severallypivotallyV connected'at one end to the abovementioned arms and at theirother ends'to bolts 2l which extend 'through the adjacent part of a ribI6 and through plates I9 bearing against opposite sides of the rib I6, Anut 22 which is cotter-pinned to a threaded endof each bolt 2i isset toprovide sliding clearance suicient for pivoting'of theerods I8 onthe`bolts 2l. The xed rib vmembers I1 are appropriately slotted, as at20, to receive the plates I8 and thereby .guide the assemblies at theupper endsoi the push rods I8. As shownin Fig. 5, in brder to eliminateexcsive 'sliding friction between the sliding' and xed cribs I6 and I1,the fixed-ribs I1 may be punched out to receive ball bearings 23, andthreaded caps 24 may b e lock-washered, as' at 25,or safety-wired inplace, to provide closey clearances for the cooperating ball bearingsl'and ribs I6, thus providing free sliding action A,without loss of'rigidity. As shown, the torque tube-I2 and auxiliary tubes, I5 and I5andthe mecha- 7g '.skin can y -of the mechanism behind that panel willbe acaczasss nisxn associated therewith are located within the wing. Themain tube I2 is preferably mounted in the region directly below .theoverlapping por-l tions of the upper skin' sections, and the push rodsoperated by it andthe rear auxiliary tube I2" are connected to movableribs I6 which are secured to the trailing section oi' the sheathcomprising the panels 26. The front auxiliary tubel I6 is operated bypush rods connected to movable ribs I6 which are secured to the leadingsection of the skin comprising the panels 29.

From the foregoing it will be evident/,that angular rotation of .themain torque and' auxiliary tubes, carrying suitable cranks having armsof appropriate lengths, will impart the'desired outward or 'inwardmovement to the movable ribsv I6, thereby causing the overlapping skinsections to move away from or toward abasic position, the

cessible. The maximum rigidityl ofthe wing is maintained at all times,since the camber-varying mechanism does not change vthe relativepositions of the spars'and the'cross-ribs. The construction does not inany way conflict with the conventional aileron 36 that is useddforlateral balance, and the ribs may be drilled or cut out for thenecessary control connections. Also, a split type ap 31 pivoted at 31'may be, and desirably'is. operated in conjunction with the variablecamber construction herein disclosed whereby these two devices willcooperate to produce further changes in the characteristics of the basicwing, and either of them may be operated independently of the other.Such changes are not equal or similar at all attitudes, and lsince bothdevices may readily be used together yeachgeas an adjunct to the other,the advantages of`th conljoint action of both may be obtained for agivensituation while by independent manipulation of either one any inherentdisadvantages thereof for a particular'situation may be minimized. l

The principles of the ninvention disclosed in Figs, 1-, 2, 3, and 3a"may be embodied in other types of airplane wing structures. For example,Figs. 6 and 6a\ together illustrate a multi-spar stressed skin wing inwhich a plurality o-f spars 40 approximately I-shaped in cross sectionextend longitudinally of the wing. JTransverse diaphragms 4I are securedto the spars 40 at spaced intervals, thus providing a rigid frame towhich the stressed skin is secured, such skin ing' of'alower stressedskin 51 and an upper stressed`skin 42, both of which are permanentlysecured to the flanges'of the spars 40 and dialragms 4 I. VIn additionto the stressed skin,

adjustable sheath or skin sectioris may be arfangedto cover either thelower or upperl portions if the stressed skin, or

both. As shown, two relaively movableA upper sheath. sections 26 and 2itre provided. The sections 26 and 29,are subtantially identical inconstruction to those al- 'eady disclosed. Furthermore the mechanism 'oradjusting the sections 26 and 29 relatively `Such mechanism consisttoone another to vary'the upper camber of the wing is generally the samein principleA as here-` inbefore disclosed, except that the main torquetube I2 is shown nearest the leading edge of the wing, `the auxiliarytubes Hand I5' being located behind the main torque tube I2, and thecranks on the several tubes being connected by drag links vwhich passopenings in the spars 40. 4 y

Since theyupper stressed skin 42 is fixed to the spars 40 and diaphragms4I, access to tle several tubes and their associated parts may beprovided by cutting openings oi' a suitable size through the skin 42directly opposite the doublearmed cranks on the several torque Itubes.These openings may be as wide as the distance between two successivecross-ribs, and are normally subfreely through suitable K stantially.closed by apertured panels 44 secured.

over the openings in the skin 42. Each panel 44 has an aperturetherethrough large enough to permitthe free movement of a push` rod I8when raising and vlowering the movable skin section to which it issecured. As shown in Figs. 6 and 7; the'push rods I6 in thisconstruction may be pivoted, as at 46, to a tting 43 which has twointegral studsi extending upward through registering holes-(in areinforcing plate 45, the overlapping or abutting margins of adjoiningpanels 26 and the bearing pla'te 28. 'I'he studs 50 project fartherupward through a slot 62 in the reinforcing and bearing plate 30, whereeach stud is drawn tight by a nut 5I to provide proper clearanceallowing for easy sliding movement of the skin sections relatively toone another.- Otherwise, the construction and operation ofvthls variablecamber Wing is substantially the same as the one shown in Figs. 3 and3a.

Suitable mechanism pilot oroperator may easily turn the main torque tubeI2 about its axis the proper amount to vary the camber as desired,`since the several torque tubes I2, I6 and I6 deslrably are rotatablymounted in antifriction bearings supported in the xed cross-ribs ordiaphragms, as vshown in Fig. 7.

is preferably located in the operators compartment, is generallyindicated at II in Fig. 1, and may consist of either: (l) a hand wheeloperating a worm and lsector gear, for hand operation; (2) a lever andholding ratchet, for `direct hand or foot operation; (3) avalve-controlled vacuum or pressure operated piston and cylinderconnected either to the intake or exhaust4 manifolds, for mechanicaloperation; or (4) a switch controlled electrical apparatus operated froma storage battery, for electrical and ,mechanical operation.

Fluid-operatedmechanism maybe employed in place o1' the torquev bes andassociated devices, to raise and -lower the relatively movable .wingsections, and'to maintain 'the latter in any one of their adjustedpositions.

to the, one shown in is provided whereby the l Figs. 6 and 6a isillustratedin Figs. 11 and l2,

and details of such Huid-operated mechanisms ,are disclosed in Figs. 13to 19, inclusive. l*As illustrated in Fig. 18 forexample, the piston 69of a single-acting cylinder 68 may be pivotally`-con nected to the pushrod I3; and uid, such as air under pressure, may beiadmittedthrough thepipe 66 to raiseithe movablewing section to which the push rod isconnected, and thereby in` crease the 'camber of the wing. Uponreleaseofthe air pressure in the `cylinder 68, a spring' 'lll operates toiorcethe piston and thepush rod I8 connected thereto back to theirinitial position, thereby decreasingrthe camber of the wing. Thecylinder 68 may be secured to a diaphragm 4| by bolts 10. The control ofthe admission and release of air pressure to the tube 66 may becontrolled from the operators compartment by suitable mechanismdesignated generally as H' in Fig. 1l. As shown in Fig. 13, thismechanism may consist of an air compressor 59 which -is connected to theairplane engine through a clutch 58 to compress air and deliver the samethrough a pipe 63 to a reservoir 60 which has a. blow-nii valve 6| andadrip cock 62. In order to prevent moisture precipitation in the tubing66 a pressure-reducing valve 64 maybe used so that the pressure in theVreservoir 60 may be greater than in the tubing' 66 that connects thereservoir to the cylinder 68. Operation of a control 'valve '65 to oneposition admits compressed air to the cylinder 68, to increase thecamber of the wing; and

similarly when the valve 65 is shut oi the air inv the tubing 66 andcylinder 68 is permittedto escape through a bleed in the valve-operatingcasing 65, whereuponl the spring 1I returns the piston 69 to its initialposition and the wing is restored to its basic high speed lcambercurvature. i

Figs. 12 and 14 illustrate lipid-actuated operating mechanism embodyingdouble-acting cylinders 12 to theopposite ends of which are'connectedseparate air supply tubings 66 and- 61.

In' thisarrangement. the operating valve 65`is constructed to feedcompressed air from the reservoir 60 to either one of the tubes 66 or61. If compressed air is supplied through operating valve 65 into line66, and line 61 is opened to the atmosphere through operating valvecasingbleed,

then piston 13 in. cylinder 12, Fig. 19, will rise and. also raise thewing skin through push rod I8 as hereinbefore described.- Similarly, ifline 66 is bled to theatmosphere, and compressed air is fed into line6-1, the piston will be forced downward, thus restoring the Wing 'skinto its basic position.

Figs. 15 and 1'7 illustrate mechanism for supplying Lhydraulic pressureto tubes 66 which are connected to single-acting cylinders similar to .I

the cylinder 68 shown in Fig. 18. vIn its simplest form this arrangementmay consist of a liquid reservoir 14, filled through a plug 15, and apivoted operating lever or pedal 16 having an arm 11 connected by a link18 to a piston 19 operating in a cylinder .8| having a liquid inlet 82communicating with the' reservoir 14. The lever 16 is accessible to thepilot and when it is depressed,

the piston 19 `ist moved forward in the cylinder y8| and forces thehydraulic liquid through th'e tubing-66, thusV causing the piston 69 ineach lactuating cylinder 68 to raise, whereupon the push rods I8connected to the pistons 69 move the upper skin sections 26 and -29outwardly.

When the lever I6 is releasedthe` Vcoil spring 68.

in the cylinder 8| forces the piston 19-to its nor- 4mal position,-whereupon the pressure in the tubing 66 is released and the springs 1Iin t e actuating cylinder 68restore the pistons 89 their initialposition and the wing sections to their normal or basic positions. Y

Fig. 16 illustrates va. hydraulic control mechanism which maybeemployedto operate doubleacting cylinders similar to the one shown inFig. 19. vHere the reservoir 14, the lever 16; andthe associatedpartsare similar to the one disclosed in detail in Fig-17, except thattwo lliquidpressure return linesA 83 and 84 are connected to thereservoir 14 and to a control valve 65 which is arranged to admithydraulic pressure to either the tubing 66 or the tubing 61. Thisarrangement is similar in general to the arrangement shown in Fig. 14,except that a closed liquid circulating system is employed.

Suitable means are provided to close the ends of the wing when the skinis positioned to increase the wing camber. As shown in Fig. 9, sheets ofsuitable flexible waterproof material 53 may be secured along one marginto a ange of each xed end rib 4| and along its other margin to themovable skin section 29 and similarly to the movable skin section 2,6,the sheets 53 being sufficiently long and wide to completely close theopposite ends of the wing when the latter is fully expanded. Fig. 10illustrates an alternative end closure which tends to reduce the endloss effect common to all airfoil forms. Here rigid vertical curvedmetal iins 54 are secured, as by rows of screws 55, to the iiange ofeach end rib 4|, in position to completely close the ends of the wing inany expanded position of the movable skin sections. A

It will be understood that numerous changes may be made in the detailsof construction as herein disclosed, and certain features of theinvention may be used without others. For example, either the lower orthe upper skin, or both, may be of a variable camber either or bothupper and lower skins may consist of a plurality of panels; or theoverlapping variable,amber skin sections may be of continuousnon-'panelled "construction while providing a lower fixed on nonvariableskin section made up of panels as disclosed to permit access to anyspace between two cross-ribs without disturbing other panels or thefaces at least one of said surfaces being a stressed t skin and one ofsaid surfaces comprising iiexible relatively movable leading andtrailing sections, the leading section overlapping the trailing section;mechanism disposed within the wing for adjusting said sectionsrelatively to each other, and Varying the sectional thickness of thewing through a predetermined range, said mechanism including devicespositively secured to each vof said movable`"sections at a plurality ofspaced points adjacent each cross-rib and arranged to simultaneously4and uniformly vary the camber of both sections to form a new cambercurvature i particularly suited to said changed Wing thickness, andmeans operatively 'connected to each of said devices constructed and'arranged to maintain each of said devices in adjusted positions at anyintermediatepoint of said predetermined range; and supporting meansarranged solely for supporting said mechanism by said wing structure,said mechanism being otherwise independent of said wing structure'whereby the structural rigidity of the wing remains unaffected.

' 2. A variable camber aircraft wing asV claimed in claim 1, inl whichsaid sections are hinged, respectively, adjacent the leading andtrailing edges of the wing, and said overlapping portions cambercurvature.

3. A variable camber aircraft wing as claimed Y in claim 1, in which-said mechanism comprises a plurality of iliuid actuateddevicesseverally operatively connected to said sections and said wingstructure. v

4. A variable camber aircraft wing as claimed ,in claim l1 in which eachof said sections has al plurality/of continuous reinforcing platessecured thereto/the plates on one section being opposed to andcooperating with the plates on the other of said sections. Y

5./A variable camber aircraft wing comprising a plurality of pairs offlxed cross-ribs, the several pairs of said cross-ribs being spacedapart of s aid fixed cross-ribs. said movable ribs being verticallyslidable in said slots and laterally supported by said fixed ribs; asheath or skin comprising relatively movable leading and trailingysections secured to said movable cross-ribs, the

leading section overlapping the trailing section; mechanism within saidwing and connected to said movable cross-ribs, for adjusting saidsections of the sheath or skin; and means for actuating said mechanism.Y

6. A variable camber aircraft wing comprising a plurality of pairs ofxed cross-ribs, the several pairs of said cross-ribs being spaced apartand the cross-ribs of' each pair being spaced to form transverseparallel-walled slots; a plurality of movable cross-ribs, said movablecross-ribs severally having web portions disposed in said slots forvertical movement relative to each respective pair of fixedcross-nbgsantifriction elements disposed. between said iixed cross-ribsand said movable cross-ribs; a sheath or skin comprising relativelymovable leading and trailing sections secured to said movablecross-ribs, the leading section overlapping the trailing section; andmechanism within`said wing and operatively conv nected to said movablecross-ribs for adjusting the position of said sections of the sheath orskin.

7. A variable camber aircraft wing comprising a frame; a sheath or skinincluding relatively movable co-operating sections having overlappingportions between the leading andtrailing edges of the wingpandmeciaanism within the wing for 4 adjusting said sections to vary thesectional thickness of the wing through a predetermined range;saidmechanism including a main rotatable torque tube and a plurality ofauxiliary rotatable tubes axially parallel to said main tube; aplurality of bell cranks secured to said main torque tubes;corresponding auxiliary bell cranks'mounted on said auxiliary tubes;link means connecting the cranks-on said main tube to the cranks on saidauxiliary tubes whereby saidcranks are caused to rotate'in unison; meansconnecting arms of said cranks to said wing sections, the relativelengths of theseveral crank arms being proportioned such that therotation of said auxiliary bell cranks is in a predetermined ratio tothe rotation of the main tube and such that the movement of saidsections is proportioned to provide the desired curvature of said wingsections.

8. A variable camber aircraft wing comprising a frame including aplurality of cross-ribs each comprising a pair of fixed, rigid andoutwardly flanged members and a movable member having a portion disposedbetweensaid pair of fixed members; anti-friction bearing means securedto said fixed members for providing free vertical movement of saidmovable member between said fixed members and for supporting saidmovable member against lateral displacement when in any position of therange of movement; a sheath or skin including relatively movableco-operating sections having overlapping portions between the leadingand trailing edges of the wings, said movable rib members being securedto said movable sections; and mechanism within the wing operativelyconnected to said movable 'members for varying the sectional thicknessof the wing.

9. A variable camber aircraft wing comprising a frame including aplurality of spars, a sheath or skin including relativelymovableco-operating sections having overlapping portions between the leadingand trailing edges yof the wing; and mechanism within the wing foradjusting said sections to vary the sectional thickness of the wingthrough a predetermined range, said mechanism comprising positivelyactuated devices located between spars, between the leading edge and aspar, and between the trailing edge and a spar, saidv devices beinginterconnected by means extending through said spars.

10. A. variable-camber aircraft wing comprising a frame; a sheath orskin comprising a stressed Askin secured to said frame, and relativelymovable co-operating cover sections having overlapping portions betweenthe leading and trailing edges of said wing, said sections beingdisposed outside of said stressed skin and normally substantiallyconforming to and bearing against a portion of said stressed skin; andmechanism within said wing for adjusting said cover sections to vary thesectional thickness of the win-g.

11. A variable camber aircraft wing which comprises a frame; a sheath orskin comprising a stressed skin secured to said frame, and relativelymovable co-operating cover sections disposed outside of said stressedskin and having overlapping portions between the leading and trailingedges of said wing; 'mechanism within said wing for adjusting `saidcover sections to vary the sectional thickness of the wing, saidmechanism including I skin is maintained.

HARRY H, STEWART.

